Optical coded document reader



Feb. 9, 1965 J. H. HOWARD 3,169,186

OPTICAL CODED DOCUMENT READER Original Filed April 9, 1956 POWER UPPLYAMPLIFIIR INVENTOR.

JOHN H. HOWARD United States Patent 3,169,186 OPTICAL CODED DOCUMENTREADER John H. Howard, Media, Pa., assignor to Burroughs Corporation,Detroit, Mich., a corporation of Michigan Original application Apr. 9,1956, Ser. No. 577,143 rtow Patent No. 2,975,966, dated Mar. 21, I961.Divided and this application July 7, 1960, Ser. No. 41,349

11 Claims. (Cl. 250-71) This invention relates to an improved datahandling system using spots of fluorescent material for data recordingand a combination of high energy light irradiation and photo sensitivescanning to read the recorded data, and is a division of applicant'sco-pending application entitled Coded Document Reader, Serial No.577,143, filed April 9, 1956, now Patent No. 2,975,966.

Data handling poses a serious problem in many fields. it is acute in thebanking industry which faces a phenomenal increase in the volume ofactivity in the handling of checking and savings accounts. Currentlythere is excessivc manual work involved-in the processing of checks andsavings records. Automation would relieve this problem. The basicdetailed activities involving the reeeipt and the payment of funds arenot the point of critical concern. It is in the necessary maintenance ofthe records relating to deposit accounting that the serious problemarises. Some method and equipment is needed to provide a data link tocentralized accounting ofiices for this processing.

Another problem area has arisen in the field of ticketing for rail andair transportation. For each ticket sold there is a need to record theserial number of the ticket and the numerical code representing thenature of the trip sold. Central accounting needs this basic informationfor interline billing, revenue accounting, and for figuring the tax duein the various states or countries through which a trip passes.

Still another problem area is currently emerging in the handling of vastvolumes of information for organizations such as government departmentsand various military or naval stafl's. In this area it is felt thatclassification and reduction of raw information preparatory to filing oranalysis could be greatly accelerated and improved in reliabilitythrough automation techniques.

Throughout many of the data handling problem areas for which automationappears desirable, there is an interest in preserving certain wellestablished forms, documents and other printed material which have awide acceptance and where the development of substitutes would be bothexpensive and of questionable advantage. The pass books, deposit ticketsand withdrawal orders in a savings bank operation are typical of suchitems. Accordingly it is considered advantageous to utilize fluorescentmaterials for practically invisible printing or coding on such documentswhich under ordinary light is inivsible and does not interfere with theordinary matter printed thereon. This luminescent material could beirradiated with high energy invisible radiation such as actinic rays,ultraviolet light or soft X-rays, and the resulting luminescentradiation utilized in the data reading and recording operation.

Difficulties arise in the use of luminescent materials in that manysubstances have some degree of fluorescent quality. Bleaches that areused in paper, inks used in the normally legible printed matter thereon,smudges from greases and other foreign materials acquired duringprocessing and handling are typical of unwanted sources of luminescentsignals which will appear on such records which are exposed to highenergy radiation. These spurious signals add to the background noiselevel and reduce the signal-to-noise ratio of desired signals and may3,169,186 Patented Feb. 9, 1965 even present such as spurious level asto introduce a false signal. The present invention is employed to readluminescent codings on records in a manner which enhances thesignal-to-noise ratio. Throughout the description of this invention, thereading of coded data on a document will be referred to as "scanning,"inasmuch as the data is recorded in a pattern of phosphorescent dotsinterspersed with areas or spots in which no phosphorescent material hasbeen deposited and these areas must be examined or scanned. Scanningcomprises the exposure of a photosensitive means to this recorded datapattern (when in an excited and radiating state) either in apredetermined sequence or with a matrix of photosensitive pickupswherein their positions correspond to particular parts of the datapattern.

An object of this invention is to provide an improveddata handlingsystem.

Another object of this invention is to provide an improved readingdevice for data recorded by phosphorescent materials.

A further object is to provide an improved signal-tonoise ratio in aluminescent scanner, wherein high energy radiation and electrical fieldsincidental to the generation of this high energy radiation and spuriousshort-persistence fluorescence are eliminated from the background levelof the signal which is picked up.

In accordance with one feature of this invention, there is provided animproved photoelectric data irradiating and reading method andapparatus, having a radiation source for producing high energy photonsto irradiate the document carrying the data, recording the data inlong-persistence phosphorescent materials, exciting this phosphorescentmaterial with this radiation and removing the radiation in apredetermined time interval" before scanning, and scanning to read thephosphorescent light which persists after short-persistence fluorescencefrom unwanted or spurious materials has subsided.

The foregoing and other objects of this invention will be readilyunderstood from the following specification and claims together with theaccompanying drawing wherein:

FIG. la is a functional diagram of an electrically controlled systemconstructed in accordance with this invention;

FIG. lb is a diagram of an amplifier useful in the system shown in FIG.la;

d FIG. lc is a plan view of a document and its coded ata;

FIG. 2 is an intensity-vs.-time plot of fluorescent and phosphorescentresponse to radiant energy.

FIG. 3 is a functional diagram illustrating photographic scanning andrecording techniques as utilized in this invention;

FIG. 4a is a front view in diagrammatic form of an optical system whichmay be utilized in accordance with this invention;

FIG. 4b is a side elevation view of the optical system of FIG. 4a; andFIGS. 15 and 6 are detailed sketches of devices featured in theinvention.

In the following description, "phosphorescence" is used for the signalluminescence having along persistence after excitation by a radiantsource and "fluorescence" is used for the noise luminescence havinglittle or no persistence after the radiation expires. A typicalphosphorescent material comprises zinc sulphide and small percentages ofadded material such as silver, with a persistence time in excess of manymicroseconds; and a typical fluorescent material is anthracene with apcrsistance time in the order of one microsecond or less."

Referring to FIG. la. an alternating voltage 20 is utilized forsynchronization of units as well as for supply and frequency may beused, consistent with required irful. Further, the duty cycle on eachpair of leads is less-- than 50%, or less than a half cycle s v. toprovide a redetermined time interval between irradiation and scanning,during which the radiation from unwanted fluorcsccnce and other noisessubsides before the desired radiation from long-persistencephosphorescent material is read.

The amplifier 32 may be of the type found in conventional dataprocessing systems. As shown diagrammatically in FIG. lb, the inputleads 30 are connected to contacts of selector 19 and the amplifierinput circuit is connected to these contacts in a predetermined sequenceso that the presence or absence of a signal, as determined by thepresence or absence of light on photocells of the scanning matrix 28,generates a digital signal which is amplified and applied to leads 33.When sources 24 and 25 are on, amplifier 32 is off; and when sources 24and 25 are off, then the amplifier 32 is on and is responsive to signalsfrom photocell assembly or matrix 28 which in turn has a plurality ofphotocells, each of which is separately responsive to incident radiationfrom a particular area or cell on the surface of document 26, which isshown in perspective in FIG. la and in plan view in FIG. 1c and whichappartaus forms the subject matter of the claims in the presentdivisional application. Data is represented in coded form on thedocument 26 by the presence or absence of phosphorescent spots 27. Otherunwanted sources of fluorescence are shown as randomly placed areas 42.

Radiant sources 24 and 25 receive energy through leads 22, producinghigh intensity radiation capable of exciting phosphorescence in therecorded phosphor spots 27 of document 26. Radiations which have beenfound useful in producing fluorescence and phosphorescence areultraviolet light, actinic rays, and soft X-rnys. in general, radiationsof wave-lengths shorter than about 6,000 Angstrom units, or yellowlight, are more useful because their energy per photon is higher.Sources 24 and 25 therefore represent producers of such well knownradiations.

Document 26, as shown in FIG. lc, utilizes both visible printed matterand invisible data recorded as spots 27 of a phosphorescent material,such as zinc sulphide. Document 26 has spots 27 arranged in a codingpattern arranged in a predetermined number of possible cell areas suchas found in a matrix so as to present important information tosupplement or confirm the visible printed information. Any well knownoptical system such as lens 29 of FIG. la serves to focus images of thisdocument coding pattern upon a corresponding matrix 28 of photocells orphototransistors, which may be positioned generally in the focal planeof lens 29. A photosensitive pickup cell is positioned in matrix 28 forthe image of each possible spot position of the pattern on document 26.When a small cell area on document 26 has phosphorescent materialapplied to form a spot 27, and irradiation has developed a detectableoutput radiation from spot 27, then lens 29 focuses this radiation uponthe particular cell of matrix 28 which corresponds to that spot 27 ondocument 26. The signals generated by cells activated in this manner arefed by leads 30 of cable 31 to amplificr 32, which serves to producecorresponding output signals at the leads 33.

Because they are invisible without processing and do not interfere withvisible printed data on document 26, spots 27 can be of comparativelylarge area and therefore positioning of document 26 is not critical. Asan alternative to large-area spots, amplifir: 32 can be constructed tobe responsive to particular signals generated by the scanning ofparticular patterns of spots 27 and of spaces on the document having nophosphorescent material. In this further case, the matrix 28 shouldextend to a greater number of positions along each co-ordinate thandocument 26 requires, so positioning still would not be critical, eventhough the relative positioning of cells in matrix 28 and of spots ondocument 26 could be a precise, finedetailed pattern. This can bevisualized by regarding the pattern or spots 27 shown on document 26 inFIG. 1c. A separate photocell of matrix 28 will be energized for eachspot 27 shown. Then, when the sampling switch of amplifier 32 contactsleads 30 in sequence, a particular sequence or signal" and "no-signal"intervals will be generated, which is characteristic of the pattern ofspots 27 ori document 26. Equipment can be made responsive to particularsequences, just as teletype equipment responds to teletypc signalsequences, and not be sensitive to which of leads 30 are used to producethis sequence. In other words, the number of photocells in matrix 28exceeds the number of coding areas on document 26, so document 26 has awide tolerance on its position beneath lens 29 in which scanning willproduce the desired sequence even though varying the position ofdocument 26 will vary the actual separate photocells transmitting thesequence via lines 30. Thus the sequence and hence the digital signal onleads 33 would not be destroyed by mispositioning of the document.

In addition to the desired luminescent material in spots 27, otherunwanted luminescent areas 42 also are present. Areas 42 on the documentare used to designate areas containing unwanted fluorescent materialssuch as dirt, grease, smudges, chemical residues, etc. Usually, they areof short-persistence fluorescence, as contrasted to spots 27 which areof long-persistence phosphorescence.

As shown in FIG. 1b, output signals are obtained from amplifier 32 atleads 33. The actual form of signals used is not pertinent to thisinvention. For example, output signals may be digital in nature, withthe digital timing determined by sampling switch of amplifier 32, andthe "on" or "off signal status determined by energization of photocellsin matrix 28 applying voltage to particular ones of leads 30. Thissampling switch must scan all leads 30 during each duty cycle as fixedby energization of leads 23. These duty cycles are time-shared with dutycycles for radiation sources 24 and 25. This time-sharing mode ofoperation presents marked improvements in the reading of normallyinvisible, luminescent markings. With radiant energy sources 24 and 25and amplifier 32 connected for continuous rather than time-sharingoperation, severe noise levels or masking background signal would beencountered, under some conditions. Analysis shows three main noises tobe present: (a) Scattered .or diffuse reflection of the incidentradiation back to photosensitive matrix 28; (b) radiation from unwantedfluoresence of bleaches, smudges and other foreign materials in areas 42on the document; and (0) electrical field noise I generated in theactivation of radiation sources, and picked up in the matrix 28 or itswiring 30. When the source of irradiation is turned off, all of thesenoises subside veryrapidly'; much more rapidly than does the radiationfrom the phosphorescent spots 27 which are of long persistence.Accordingly, spots 27 continue to energize cells of matrix 28 afterbackground noise subsides, providing a marked improvement insignal-to-noise ratio over prior art reading techniques. Preferably alight-tight enclosure-shown here, for illustrative purposes, with thefront wall removed-is provided by walls 34 surrounding thedocument-scanning position and connected to the structure of sources24-and 25 to reduce any refiection, excitation or diffusion fromexternally incident radiant energy.

FIG. 2 illustrates the time relationshipsof the novel mode of operationsuggested by the present invpntion.

Radiation sources 24 and are on for the pulse period 43 from zero (0) toT during which all fluorescent materials 42 rise to a radiation outputamplitude related to the incident radiation, as shown by the leadingedge 44 of waveform 40. During this same interval, 0 to T allfluorescent materials of spots 27 also rise to a maximum radiationoutput related to incident radiation as shown by the leading edge 46 ofwaveform 41. For convenience, these are indicated as a common level Imreached under sustained irradiation at time T The radiation sources 7.4and 25 are cut off at time T and the photosensitive pickup system ofphotocell matrix 28 and amplifier 32 is energized at time T During thisinterval T -T,, the unwanted fluorescence of dirt, chemical residues,dirt. ctc.,-shown on the document as spots 42 will decay rapidly. Thetrailing edge 45 of curve 40 shows a typical radiation decay curve forsuch fluorescent materials as spots 42. Contrasted to curve 40, thedecay time for phosphorescent materials in coded spots 27 isconsiderably longer, as shown by the trailing edge 47 of curve 41.Beginning at time T and for a period f -T the photocell matrix 28responds to radiation from spots 27 and amplifier 32 responds to thesignals from matrix 28. Since a delay time has been provided duringwhich radiation from unwantel fluorescence has subsided, there will belittle or no signal from areas 42. From an examination of curves 40 and41 it can be seen that the ratio of signal (curve 41) to noise (curve40) during this period T -T, is increased considerably over that insystems employing continuous irradiation. To this is added the increasein ratio of wanted signal to unwanted radiation and noise, arising fromremoval of incident irradiation and electrical noise which also affectthe signal-tonoise ratio adversely.

In lieu of an electrical output signal at leads 33, the photosensitivepickup matrix 28 can be replaced by a recording camera 35, as shown inFIG. 3. Camera is mounted with an electrically actuated shutter 36functioning to open for passage of radiation when a voltage is appliedto leads 23. Radiation sources 24 and 25 function as described before.When X-rays are used. appro priate shielding must be included in housing34 and around the camera 35. The time relationship between voltagesapplied to leads 22 and 23 is shown by waveforms 37 and 38. Theradiation sources 24 and 25 irradiate document 26 during a pulse of wave37. After this irradiation. shutter 36 is opened and the film 39 incamera 35 is exposed to the phosphorescent radiation from spots 27. Thecontrast characteristic of film 39 can be selected to provide maximumdiscrimination against the lower level light from the unwantedfluorescent materials. shown as curve 40 in FIG. 2, and maximum emphasisof the higher level light from the phosphorescent materials of spots 27,shown as curve 41 in FIG. 2. It is evident that with film 39 anddocument 26 statically positioned, the waveforms 37 and 38 will actuateradiation sources 24 and 25 and shutter 36 to produce multiple exposureswhich emphasize the long-persistence phosphorescent radiation from spots27. However film 39 can be fed automatically by mechanisms such as thatin the commercially available Robot" camera and documents also can befed in an automatic manner. Both automatic feeds can be triggcred ordriven by waveforms 37 and 38, through solenoids or quick startingelectric motors, in ways well known to those skilled in the art. Suchautomatic feed of film and documents would be useful to record a numberof documents when a single high-intensity irradiation of a document andsubsequent exposure of the film produces adequate density of theresulting photograph. Further a manual switch could be used to switch avoltage source from a normal position on line 22 to a scanning positionon line 23. As this switch is actuated, radiation sources 24 and 25 arecut off, fluorescence of areas 42 subsides, leaving phosphorescence ofspots 27, and shutter 36 is opened to record the radiation from spots27.

As shown in FIGS. 40 and 4b, and in accordance with the form of thepresent invention claimed in the parent application identified above,the time delay between irradiation and scanning, necessary to permitunwanted fluorescence to subside before desired phosphorescence isscanned, is provided by an optical system. FIG. 4a is a front elevationview of a housing 34, with its front wall removed, for a rotating mirrorassembly 50, with document 26, radiation source 57, and photoelectriccell 58 facing the mirror assembly as shown. With reference to FIG. 4bit will be seen that source 57 and cell 58 are immediately belowdocument 26 and that rotating mirror assembly is driven by motor 60.Mirror assembly 50 comprises five plane mirrors 51 to mounted around theaxis of rotation to form a pentagon. It is evident that either greateror lesser numbers of mirrors could be so mounted, forming a triangle,square, hexagon, etc. Each plane mirror 51 to 55 is tilted at an anglerelative to the axis of rotation of mirror assembly 50 which isdifferent from the tilt angle for other mirrors, so that each mirrorreflects a ray from source 57 to a different area of document 26, aswill now be described.

Radiation source 57 includes a collimator to align its outgoingradiation into ray 56. Ray 56 strikes whichever mirror of mirrors 51 to55 is positioned to reflect it. As shown in FIG. 411, mirror 52 is insuch a position and reflects my 56 back to document 26. Photocell 58also includes a collimator aligned with ray path 59. In effect,photocell 58 can see" only the small area of document 26 aligned withray 59. With mirror assembly 50 rotating counterclockwise as shown inFIG. 4a, the portions of rays 56 and 59 from mirrors to document 26,will sweep across the document from left to right. If the planes of allmirrors 51 to 55 were mounted at the same angle relative to the axis ofrotation, then the successive sweeps of rays 56 and 59 across document26 would be on the same path across the document for reflection fromeach mirror. However, each mirro has its plane at a different anglerelative to the axis of rotation. These differing angles of tilt areshown as dotted lines 64 and 65 in FIG. 4b. Only two such angles of tiltare shown to simplify the drawing. Line 64 of less tilt than line 65 isthe plane of mirror 54 of minimum tilt angle, while line 65 would be formirror 55 of maximum tilt angle.

As shown in FIG. 40, mirror 54 has minimum or zero tilt, mirror 53 hasnext larger tilt angle, mirror 52 has next larger tilt angle, and so onuntil the last successive mirror, mirror 55 of the pentagon, is reached.Then the first mirror 54 again comes around to return the rays to thepath for minimum tilt angle. As shown in FIG. 4b. this axial tilt causesthe rays 56a, b and c together with their corresponding rays 59, forradiant energy and for the "viewing ray" of theh photocell respectively,to sweep document 26 along a different line for each mirror. Line 56a isthe raypath from mirror 54 to document 26, line 56b is the ray path frommirror 52 to document 26, and line 56c is the ray path from mirror 55 todocument 26. Accordingly, it is evident that, in addition to the sweepof rays 56 and 59 across the document from left to right as seen in FIG.40, there is a displacement of each sweep to a separate path as shown inFIG. 4b, as motor rotates the mirror assembly 50. Because of the spacedrelation of rays 56 and 59 and the direction of rotation of mirror 50,ray 59, or the viewing ray of photocell 58 sweeps over any given area ofdocument 26 shortly after that spot is irradiated by ray 56. The speedof rotation of mirror 50 can be utilized to adjusted the time intervalbetween irradiation and scanning. Motor 60 is preferably provided with avariable speed drive for this purpose. However, in determining a speedof rotation needed for a given sweep speed of rays 56 and 59 acrossdocument26, it must be remembered that the angular velocity of the rayssweeping across document 26 is twice the angular velocity of mirrorsystem 50. This relation exists because the angle of incidence equalsthe angle of reflection and the source and document are both stationary.Consider movement of the mirror through, say, degrees rotation. Thischanges the angle of incidence of a ray the same 5 degrees. This in turnchanges the rays angle of reflection another 5 degrees, so the anglebetween incident and reflected rays has changed degrees.

With this optical method of introducing a time delay between irradiationand scanning so that fluorescence can subside, it is unnecessary to gatewith electrical signals the source 57 or detector device 58. The outputsignal from detector device 58 will be dependent upon spotscanningspeeds, spot distribution on the document, and persistence time forspots 27. The first two parameters generate the signals conveying theinformation stored in the spots, and the last parameter affects theratio of this signal to background noise, the noise including radiationfrom unwanted fluorescene. As shown in FIGS. 40 and 4b, with amulti-sided mirror and with each mirror tilted to scan a different lineor zone of the document, a large matrix of digitally coded informationcan be scanned in a very short interval to develop serially presentedelectrical signals at the photocell 58. The number of separate linesfrom which coded data may be read, as seen in FIG. 4b, is determined bythe number of differently tilted plane mirrors in mirror system 50. Eachtilt angle places the ray paths on a different line. The output signalsof detector device 58 will be digital in nature, due to the scanningsequence of the ray paths generated by rotating mirror system 50.

Time sharing between irradiation and scanning may be providedmechanically in the embodiment shown in F168. 5 and 6, and as claimed inco-pending divisional appliction of the above-identified parentapplication Serial No. 4l,350, filed July 7, 1960, now Patent No.3,051,836. Disc 61 is rotated, presenting aperture 62 first to radiationsource 57 and then to the photosensitive pickup device 58 which are thesame general types as those used in FIGS. 40 and 4b. For more adequatescanning, a plurality of apertures can be provided and the source andpickup positioned to insure that irradiation is cut off before thepickup cell is exposed to luminescent sources of radiation. In thisinterval between irradiation and exposure oi the cell, unwantedfluorescence subsides and then the desired phosphorescence from spot 27activates the photosensitive pickup more reliably due to the reducedbackground noise, providing an enhanced signal to noise ratio. Scanningis provided either through motion of document 26 or by conventionalNipkow disc techniques, with rotation of disc 61 providing very frequent"looks at document 26 so no spots 27 or untreated areas for such a spotare missed as either document 26 or the disc aperture pattern is moved.Since the exposure of photocell 58 is in short, frequently repeatedintervals, it provides a basic signal frequency when radiation isreceived, so a digital signal is provided on an alternating "carrier"voltage, the frequency of which is determined by the freuency of passageof aperture 62.

From an examination of these embodiments of-thls invention it is seenthat the reading of data which has been deposited in luminescentmaterial upon a document is markedly improved in reliability and in thereduction of errors or spurious signals through the use oflong-persistence material for such data and in reading the radiationfrom this material after it is no longer exposed to irradiation andshort-persistence luminescence from unwanted luminescence sources hassubsided. As in most communication systems of limited intrinsicresolving power, increase in the signal-to-noise ratio can be dependedupon to improve reliability of the system's performance.

What is claimed is:

1. Apparatus for reading a document upon which data is coded in apattern comprising a plurality of discrete areas of long persistentluminescent materials and upon which short persistent luminescentmaterial may be deposited incident to processing and handling of saiddocument, said apparatus comprising means simultaneously to irradiatethe materials on said document, detector means to receive radiation fromsaid coded pattern of materials on said document, and means to controlsaid irradiating means and said detector means in a manner operable toestablish predetermined time periods between irradiation of saidmaterial and radiation reception to enable said detector means torespond only to radiation from said long persistent luminescentmaterials and only after radiation from said short persistentluminescent materials has subsided, said control means causing saidirradiating means to be energized for an appropriate time period andthereafter de-encrgizcd to permit radiation from said short persistentluminescent materials to subside, said control means further causingsaid detector means to respond after a predetermined time period toradiation from said long persistent luminescent materials and in theabsence of any additional irradiating source, said detector meanscomprising means positioned in an optical system and operablesimultaneously to record the whole pattern of long persistentluminescent materials deposited on said document.-

2. Apparatus for reading a docttmcnt upon which data is coded in apattern comprising a plurality of areas of long persistent luminescentmaterials and upon which short persistent luminescent materials may bedeposited incident to processing and handling of said document, saidapparatus comprising, means to irradiate the materials on said document,detector means to receive radiation simultaneously from all the distinctareas of the pattern of coded data on said document, and means tocontrol said irradiating means and said detector means in a manneroperable to establish predetermined time periods between irradiation ofsaid material and radiation reception to enable said detector means torespond to radiation from said long persistent luminescent materialsonly after radiation from said short persistent luminescent materialshas subsided, said control means causing said irradiating means to beenergized for an appropriate time period and thereafter de-energized topermit radiation from said short persistent luminescent materials tosubside, said control means further causing said detector means torespond after a predetermined time period to radiation from said longpersistent luminescent materials and in the absence of any additionalirradiating source, said detector means comprising a plurality ofphotocells positioned in an optical system and each separately butsimultaneously responsive to incident radiation from a particular areaof said coded data pattern, and said photocells provide electricalsignals representative of the pattern of long-persistent luminescentmaterials deposited on said document.

3. Apparatus for reading a document upon which data is coded in apattern comprising a plurality of areas of long persistent luminescentmaterials and upon which short persistent luminescent materials may bedeposited incident to processing and handling of said document, saidapparatus comprising, means to irradiate the materials on said document,detector means to receive radiation simul- I taneously from all thedistinct areas of the pattern of coded data on said document, means tocontrol said irradiating mcans and said detector means in a manneroperable to establish predetermined time periods between irradiation ofsaid material and radiation reception to enable said detector means torespond-to radiation from said long persistent luminescent materialsonly after radiation from said short persistent luminescent materialshas subsided, said detector means comprising a plurality of photocellspositioned in an optical system and each separately but simultaneouslyresponsive to incident radiation from a particular area of said codeddata pattern, said photocells providing electrical signalsrepresentative of the pattern of long-persistent luminescent materialsdeposited on said document, and an amplifier for receiving signals fromsaid plurality of photocells and providing an output a 9' signalrepresentative of said data, wherein said control means comprises anenergizing means which energizes said irradiating means and saidamplifier in separate and successive intervals.

4. Apparatus-for reading a document upon which data is coded in apattern comprising a plurality of areas of long persistent luminescentmaterials and upon which short persistent luminescent materials may bedeposited incident to processing and handling of said document, saidapparatus comprising, means to irradiate the materials on said document,detector means to receive radiation simultaneously from all the distinctareas of the pattern of coded data on said document, means to controlsaid irradiating means and said detector means in a manner operable toestablish predetermined time periods between irradiation of saidmaterial and radiation reception to enable said detector means torespond to radiation from said long persistent luminescent materialsonly after radiation from said short persistent luminescent materialshas subsided, said detector means comprising a plurality of photoccllsassembled in a matrix corresponding to the pattern of the data coded inlong persistent luminescent materials on said document, said photocellspositioned in an optical system and each separately but simultaneouslyresponsive to incident radiation front a particular area of said codeddata pattern, said photocells providing electrical signalsrepresentative of the pattern of long-persistent luminescent materialsdeposited on said document. and an amplifier receiving signals from saidplurality of photocells and providing an output signal representative ofsaid data, wherein said control means comprises an energizing meanswhich energizes said irradiating means and said amplifier in separateand successive intervals.

5. Apparatus for reading a document upon which data is coded in apattern comprising a plurality of discrete areas of long persistentluminescent materials and upon which short persistent luminescentmaterials may be deposited incident to processing and handling of saiddocument, said apparatus comprising, means simultaneously is irradiatethe materials on said document, detector means to receive radiation fromsaid coded pattern of materials on said document, and means to controlsaid irradiating means and said detector means in a manner operable toestablish predetermined time periods between irradiation of saidmaterial and radiation reception to enable said detcctor means torespond only to radiation from said long persistent luminescentmaterials and only after radiation from said short persistentluminescent materials has subsided, said detector means comprising meanspositioned in an optical system and operable simultaneously to recordthe whole pattern of long persistent luminescent materials dcpositcd onsaid document, and wherein said control means comprises an energizingmeans which energizes said irradiating means and said optical recorderin separate and successive intervals.

6. An apparatus for recognizing articles bearing phosphorcseentmarkings; said apparatus comprising: scanning means; excitation means,effective when energized for exciting the phosphorescent markings; meansoperativcly associated with said excitation means for alternatclyenergizing and de-cnergizing the excitation means while each of saidphosphorescent markings is adjacent said scanning means; and arecognition channel operativcly associated with said scanning means forproducing a distinctive output in response to the after-glow emission oflight from each one of said phosphorescent markings to said scanningmeans while said excitation source is dc-energizcd after beingenergized.

7. Apparatus for recognizing an article bearing markings in the form oflong persistent luminescent material, said apparatus comprising: meansfor irradiating the luminescent material on said article, detector meansto receive radiation from said luminescent material on said article, andmeans to control said irradiating means in a manner operable toestablish predetermined time periods of irradiation of said luminescentmaterial separated by time periods of non-irradiation of said materialin order to enable said detector means to respond to the radiation fromthe long persistent luminescent material during the time periods ofnon-irradiation, said control means causing said irradiating means to bealternately energized and de-cnergizcd for appropriate time periods andfurther causing said detector means to respond to radiation from saidlong persistent luminescent material during said time periods ofde-energization and in the absence of any additional irradiating source,said detector means being positioned in optical relation to the articleand being operable to provide a distinctive output in response to theemission from said long persistent luminescent material borne by thearticle while the irradiating means is de-energizcd.

8. The invention described in claim 7 characterized in that the detectormeans includes an assembly of photocells optically disposed to receivelight from different portions of the article.

9. The invention described in claim 7 characterized in that the detectormeans is constituted by a camera capable of recording the radiationreceived thereby on a film.

10. Apparatus for recognizing an article bearing markings in the form ofshort and long persistent luminescent materials, said apparatuscomprising: excitation means, effective when energized, for irradiatingthe luminescent materials on said article, detector means arranged toreceive radiation from said luminescent materials on said article, andmeans to control said excitation means and said detector means in amanner operable to establish predetermined time periods of irradiationof said materials separated by time periods of non-irradiation of saidmaterials in order to enable said detector means to respond only to theradiation from said long persistent luminescent material, said controlmeans alternately energizing and de-cncrgizing said excitation means forappropriate time periods and causing said detector means to be effectiveduring the time periods of the de-cncrgization of the excitation meansin order to respond to radiation from only said long persistentluminescent material, and means operatively associated with saiddetector means for providing a recognizable output in response toemission from the long persistent luminescent material during a timeperiod of de-energization of the excitation means.

ll. Apparatus for recognizing an article bearing markings of longpersistent luminescent material and upon which short persistentluminescent material may be deposited, said apparatus comprising meansfor irradating the luminescent markings on said article, detector meanspositioned in optical relation to the article in order to receiveradiation from said luminescent markings thereon, and means to controlsaid irradiating means and said detector means in a manner tov establishtime periods between irradiation of said luminescent materials andradiation reception therefrom in order to enable said detector means torespond only to radiation from said long persistent luminescentmaterials and after radiation from said short persistent luminescentmaterials has subsided, said detector means having means for producing asignal in response to the reception of radiation from said luminescentmaterials, and said control means governing the operation of saidirradiating means and providing successive time periods of irradiationand nonirradiation of the luminescent markings on the articles andfurther governing the operation of the detector means so that itprovides a distinctive output in response to the receipt thereby ofradiation from the long persistent luminescent material during a timeperiod of non-irradiation of the luminescent markings.

(References on following page) References Cited in the 1116 of thispatent UNITED STATES PATENTS 12 Rajchman Apr. 17, 1956 Johnson July 24,1956 Cellmer June 4, 1957 Po11ock Jan. 6, 1959 Toulmin May 26, 1959Edholm Oct. 18, 1960 Yacger Apr. 3, 1962

7. APPARATUS FOR RECOGNIZING AN ARTICLE BEARING MARKINGS IN THE FORM OFLONG PERSISTENT LUMINESCENT MATERIAL, SAID APPARATUS COMPRISING: MEANSFOR IRRADIATING THE LUMINESCENT MATERIAL ON SAID ARTICLE, DETECTOR MEANSTO RECEIVE RADIATION FROM SAID LUMINESCENT MATERIAL ON SAID ARTICLE, ANDMEANS TO CONTROL SAID IRRADIATING MEANS IN A MANNER OPERABLE TOESTABLISH PREDETERMINED TIME PERIODS OF IRRADIATION OF SAID LUMINESCENTMATERIAL SEPARATED BY TIME PERIODS OF NON-IRRADIATION OF SAID MATERIALIN ORDER TO ENABLE SAID DETECTOR MEANS TO RESPOND TO THE RADIATION FROMTHE LONG PERSISTENT LUMINESCENT MATERIAL DURING THE TIME PERIODS OFNON-IRRADIATION, SAID CONTROL MEANS CAUSING SAID IRRADIATING MEANS TO BEALTERNATELY ENERGIZED AND DE-ENERGIZED FOR APPROPRIATE TIME PERIODS ANDFURTHER CAUSING SAID DETECTOR MEANS TO RESPOND TO RADIATION FROM SAIDLONG PERSISTENT LUMINESCENT MATERIAL DURING SAID TIME PERIODS OFDE-ENERGIZATION AND IN THE ABSENCE OF ANY ADDITIONAL IRRADIATING SOURCE,SAID DETECTOR MEANS BEING POSITIONED IN OPTICAL RELATION TO THE ARTICLEAND BEING OPERABLE TO PROVIDE A DISTINCTIVE OUTPUT IN RESPONSE TO THEEMISSION FROM SAID LONG PERSISTENT LUMINESCENT MATERIAL BORNE BY THEARTICLE WHILE THE IRRADIATING MEANS IS DE-ENERGIZED.